Device for degassing a sample

ABSTRACT

Device for degassing a sample and measuring the gas therein having a vertically movable chamber for the sample which in its upper sample loading position includes actuating means to flow a curtain of protective gas therearound and further includes carrier gas flowing through the chamber in both the upper loading position and the lower testing position.

United States Patent Boillot Ma 28, 1974 DEVICE FOR DEGASSING A SAMPLE [56] References Cited [75] Inventor: Pierre Boillot, Le Pecq, France UNITED STATES PATENTS AssigneeZ lnstitut De Recherches De La 3,i88,180 6/1965 Holler 73/19 Siderurgie Francaise, Saint Germain en Laye, France Primary ExammerJames J. Glli [22] F] d A 7 1972 Assistant Examiner-Anthony V. Ciarlante 1 e ug.

[2l Appl. No.: 278,208 ABSTRACT Device for degassing a sample and measuring the gas [30] Foreign Application Priority Data therein having a vertically movable chamber for the A 12 197! F 29 sample which in its upper sample loading position inrance 507 cludes actuating means to flow a curtain of protective gas therearound and further includes carrier gas flowlll. ing through the chamber in both the upper 10a ding [58] Field n73/l9 Sition and the lower testing position 8 Claims, 2 Drawing Figures DEVICE FOR DEGASSING A SAMPLE The invention relates to a device for degassing a sample and for use in a measurement sequence employed in determining the quantities of various gases present in a sample.

Such a measurement sequence generally includes a device in which the sample is subjected to a treatment known as degassing so as to release various gases present in the sample. The gases released in this manner are introduced into a device which effects the measurement of the respective quantities of the various gases released.

The degassing treatment of the sample consists in heating, which can be at a temperature up to the melting point of the sample, in a chamber known as a degassing chamber, and discharging the released gases to the measurement device, generally by providing a gas known as the carrier gas to flow through the degassing chamber. The nature of the carrier gas and the choice of gases, the quantities of which are measured downstream of the degassing chamber, depend on the type of analysis and of the measurement taken. The measurement sequence may include a device for the selection of the various gases released from the degassing chamber.

A degassing chamber through which the carrier gas flows as described above generally includes an enclosure for the treatment of the sample by heating. The sample may be heated by a heating device consisting of an inductor winding surrounding the treatment enclosure. Alternatively, the sample may be heated by the direct passage of a current of high intensity into a crucible containing the sample. The degassing chamber also has orifices for supplying the carrier gas and the evacuation of the carrier gas and of the gases released from the sample, an obturation member making it possible to introduce and remove the sample and to close the chamber during the degassing of the sample, a support for the sample and a cooling device for preventing excessive heating of certain portions of the degassing chamber.

In order to avoid the uncontrolled introduction of gaseous elements from the atmosphere causing disturbances in the degassing chamber, -a curtain of protective gas can be formed at the entry to the chamber.

A relatively long time is required for submitting a sample to a degassing operation in a degassing cham ber as described above. Moreover, it is important to insure that all of the gases released by the degassing treatment are discharged downstream of the degassing chamber to the measurement device.

With this aim in view, the invention provides a device for degassing a sample comprising a degassing chamber which when in use has carrier gas flowing therethrough; having a treatment enclosure for heating a sample; a movable support element for the sample; an obturation member for the degassing chamber; means for forming a curtain of protective gas at an entrance of the chamber; and means connecting the support element and the obturation member and for controlling simultaneously the'respective movements of the support element and of the obturation member.

The evacuation of. gases released by the degassing treatment may be effected by a continuous suction channel extending from the heated zone of the degassing chamber to the outside of the degassing chamber so that the gases released from the sample do not come into direct contact with any cold wall of the degassing chamber.

The discharge channel may be provided by an axial cavity formed in the support element.

The control device for the respective movements of the support element and the obturation member may actuate, at the instant of the opening and of the closing of the degassing chamber, a control device for the means for forming the curtain of protective gas at the entrance to the degassing chamber for the entire duration of the chamber opening.

A device according to the invention enables the degassing of a sample to be effected rapidly without special operational precuations being taken while eliminating factors tending to vitiate the accuracy of the subsequent measurement.

The simultaneous movement of the support element for the sample, the movement of the obturating member of the degassing chamber and the releasing or stopping movement of the means for forming the curtain of protective gas for the chamber make it possible to introduce or remove'the sample in a single operation and under satisfactory conditions of protection from the atmosphere. The structural arrangement of the support element moreover makes it possible to insure the removal of all of the gases released from the sample, in particular when these gasestend to settle on a cooled wall, as is the case with hydrogen.

A degassing chamber embodying the invention is described below, by way of example, with eference to the accompanying drawings, in which:

FIG. 1 shows a diagrammatic view of a device according to the invention, the degassing chamber being shown as it is beginning to open; and

FIG. 2 shows a longitudinal section, partly cut away,

of the device of FIG. 1, the degassing chamber being closed.

The device shown in FIG. 1 comprises a vessel defining a degassing chamber 1 rigidly attached to a fixed framework 2. In the upper portion of the chamber 1 is an obturating member 3. A support element 4 for a sample is movable along the axis of the degassing chamber 1. The'obturating member 3 and the support member are rigidly attached to an axially movable structure constituted by an upper .cross piece 5 and a lower cross piece 6 which are connected together by uprights 7 and 8. The lower cross piece 6 is connected to the uprights 7 and 8 by means of springs 9 and 10 in such a manner that the lower cross piece 6 can undergo an axial translation movement relative to the uprights 7 and 8 while compressing the said springs. The support element 4 is rigidly attached to the lower cross piece 6 bycollars 11 and 12 and is free to rotate in relation to the cross piece 6 but is axially movable therewith. The support element 4 includes a guide lug 13 whose ends can engage in guide ramps 14 and 15, each having a vertical portion and a portion inclined relative to the horizontal, the ramps 14 and 15 being formed in a bushing 16 which is rigidly attached to the-framework 2 so as to constitute a bayonet coupling. The support element 4 is provided with an operating handle 17 which enables rotative movement and axial translation to be imparted to it. A clamp 18 (FIG. 2) is rigidly attached to the framework 2 and has a clamping screw for clamping the support element 4 in any desired position. A stop member 19, which is rigidly attached to one of the uprights, acts on a switch at the instant of the opening and of the closing of the degassing chamber 1 to initiate and stop, respectively, a flow of gas for forming a protective curtain at the entrance to the degassing chamber as is explained below.

Referring now to FIG. 2, the degassing chamber 1 is provided with an upper head 20 having an annular cavity 21 for circulation of a cooling fluid and an annular cavity 22 provided with orifices 23 which open into the upper end of an axial cavity 24 for the formation of a curtain of protective gas. The sealing of the degassing chamber, when closed, is insured by a joint 25. The axial cavity 24 opens at its lower end into a recess having housings for sealing joints and in which is detachably engaged the upper end of a treatment enclosure 26 consisting, for instance, of an upright quartz tube. An inductor heating winding 27 is arranged around the enclosure 26. The lower end of the treatment enclosure 26 is engaged in a similar manner in a recess of a lower head 28 having an annular cavity 29 for circulation of a cooling fluid and an axial cavity 30 for passage of the support element 4. A lip joint 31 arranged in the cavity permits axial displacement of the support element 4 in the axial cavity while insuring a gas-tightness of the degassing chamber.

The support element 4 is a tube 32 on which can be arranged directly or by means of an intermediate member (not shown in the drawing) a crucible 33 for receiving an analysis sample. The tube 32 has, at its upper end gaps 34 which put the interior of the tube 32 into communicationwith the space between the tube and the treatment enclosure 26. The tube 32 is connected at its lower end to a flexible channel 35 through which the gases of the degassing chamber can be discharged to measurement apparatus arranged downstream.

The degassing chamber 1 functions as follows:

At the moment, when a metal sample is introduced, the movable structure being in its upper position, the degassing chamber is open and is protected from the atmosphere by a curtain of protective gas. The obturation member 3 is cleared from the entrance to the chamber by the upper cross piece of the movable structure, and the stop member 19 does not act on the switch for controlling stopping of the flow of protective gas. The crucible 33 is in the axial cavity 24 of the upperhead and below the curtain of protective gas. The sample is introduced into the crucible 33 through the gaseous curtain and the movable structure is lowered by means of the operating handle 17, which simultaneously causes the obturating member 3 and the support element 4 to descend, the curtain of protective gas being maintained until the movement when the lower face of the obturating member reaches the sealing joint 25. At this moment the ends of the guide lug 13 are at the bottom of the vertical portion of the guide ramps 14, 15, respectively, and the stop member ll9 acts on the control switch and thereby stops the flow of protecftive gas. The exact moment when the switch is acted v the lower cross piece 6 by the collar ll thereby to,

compress the springs 9 and 10. The compression force of the springs 9 and 10 is transmitted by means of the uprights 7 and 8 and the upper cross piece 5 to the obturation member in such a manner as to apply the obturation member against the sealing joint 25 with a corresponding force. The sample is then in the central zone of the treatment enclosure and can be subjected to in duction heating.

it should be noted that the carrier gas flowing through the degassing chamber is continuously maintained, the carrier gas being introduced through the orifices 23 through which the protective gas enters, the difference between the gaseous flows in the open position and in the closed position of the obturation member 3 determining their respective rates of flow. The heating of the sample is effected in such a manner that the gases present in the sample are released. The released gases penetrate with the carrier gas through the openings 34 into the tube 32 and are discharged through the flexible channel 35 towards a measurement device arranged downstream of the degassing chamber. The openings 34, when the sample is heated, are in the heated zone of the degassing chamber and the released gases are discharged through the tube 32 without being able to come into contact with the cold walls of the lower head 28. i

As soon as the measurement operation is finished, the handle 17 is moved in a direction opposite that which is described above so as to bring the movable structure back to its upper position and thus enable a further sample to be introduced into the degassing chamber. 7

A device chamber such as described above can be used where it is desired to determine rapidly the quantities of the gas present in a sample, in particular, a sample of a metal in the process of being treated, since the total measurement time practically depends only on the response time of measurement apparatus arranged downstream of the degassing chamber. The handling operation of the sample in the degassing chamber itself take y b t ssssnfls-Mwswsa by h 99 ...llll tion of the device described above, the error factor inherent in the degassing treatment, which factor tends to falsify the interpretation of the measurement result, is removed.

What I claim is: 1. A device for degassing a sample comprising a degassing chamber having an entrance and a treatment enclosure for heat treating a sample positioned therein; said chamber having a longitudinal axis;

a support member mounted in said chamber for supporting the sample; said support member being movable along said axis between a sample loading position located at the entrance of said degassing chamber and a sample testing position located in said treatment enclosure; an obturation member provided for said chamber, said obturation member being selectively openable and closable; means providing carrier gas flowing through said chamber; means providing a curtain of protective gas at said chamber entrance when said obturation member is in an open position, and means connecting said support element and said obturation member for simultaneously opening and closing said obturation member with respect to the position of said support element within said degassing chamber.

2. A device according to claim 1 in which said enclosure and said support are concentrically arranged tubes, and openings are provided in said-support tube to allow gases released from said sample to pass therein.

3. A device according to claim 1 in which a discharge channel extends from said enclosure to outside of said chamber.

4. A device according to claim 3 in which said discharge channel is an axial cavity connected to said onclosure.

5. A device according to claim 1 in which said control means comprises an element initiating actuation of said protective gas means to allow said protective gas to flow when said enclosure is in the sample loading position and for stopping said actuation when said enclosure is in the sample testing position.

6. A device for degassing a sample, comprising a degassing chamber, said chamber having a treatment enclosure region for heat treating of a sample enclosed therein and an entrance region with an aperture and adjoining said treatment enclosure region, a sample support member movably mounted in said chamber between a sample loading position in said entrance region and a sample testing position in said treatment enclosure region, a movable obturation member having a first position spaced from said aperture to permit access to said entrance region through said aperture and a second position sealingly closing said aperture, gas inlet means in said entrance region for providing a curtain of protective gas at said entrance region in said first position of said obturation member, and common control means for moving said support member and obturation member, whereby said support member is moved to said loading position when the obturation member is in said first position, and said support member is moved to said testing position when said obturation member is in said second position.

7. The device of claim 6 wherein said degassing chamber comprises a cylinder, one end of said cylinder forms said entrance region, and the central portion thereof forms said treatment region, and further comprising means extending through the other end of said cylinder for axially moving said support member in said chamber.

8. The device of claim 7 wherein said means extending through said other end of said chamber comprises gas discharge tube means for withdrawing gases from said chamber. 

1. A device for degassing a sample comprising a degassing chamber having an entrance and a treatment enclosure for heat treating a sample positioned therein; said chamber having a longitudinal axis; a support member mounted in said chamber for supporting the sample; said support member being movable along said axis between a sample loading position located at the entrance of said degassing chamber and a sample testing position located in said treatment enclosure; an obturation member provided for said chamber, said obturation member being selectively openable and closable; means providing carrier gas flowing through said chamber; means providing a curtain of protective gas at said chamber entrance when said obturation member is in an open position, and means connecting said support element and said obturation member for simultaneously opening and closing said obturation member with respect to the position of said support element within said degassing chamber.
 2. A device according to claim 1 in which said enclosure and said support are concentrically arranged tubes, and openings are provided in said support tube to allow gases released from said sample to pass therein.
 3. A device according to claim 1 in which a discharge channel extends from said enclosure to outside of said chamber.
 4. A device according to claim 3 in which said discharge channel is an axial cavity connected to said enclosure.
 5. A device according to claim 1 in which said control means comprises an element initiating actuation of said protective gas means to allow said protective gas to flow when said enclosure is in the sample loading position and for stopping said actuation when said enclosure is in the sample testing position.
 6. A device for degassing a sample, comprising a degassing chamber, said chamber having a treatment enclosure region for heat treating of a sample enclosed therein and an entrance region with an aperture and adjoining said treatment enclosure region, a sample support member movably mounted in said chamber between a sample loading position in said entrance region and a sample testing position in said treatment enclosure region, a movable obturation member having a first position spaced from said aperture to permit access to said entrance region through said aperture and a second position sealingly closing said aperture, gas inlet means in said entrance region for providing a curtain of protective gas at said entrance region in said first position of said obturation member, and common control means for moving said support member and obturation member, whereby said support member is moved to said loading position when the obturation member is in said first position, and said support member is moved to said testing position when said obturaTion member is in said second position.
 7. The device of claim 6 wherein said degassing chamber comprises a cylinder, one end of said cylinder forms said entrance region, and the central portion thereof forms said treatment region, and further comprising means extending through the other end of said cylinder for axially moving said support member in said chamber.
 8. The device of claim 7 wherein said means extending through said other end of said chamber comprises gas discharge tube means for withdrawing gases from said chamber. 